Absorbent articles, such as disposable diapers, sanitary napkins, pantiliners, incontinence pads, tampons, and the like are typically utilized for absorbing body fluids such as urine, feces, vaginal fluids, and menses. Upon absorbing these fluids, the absorbent articles can be found to contain a number of volatile chemical compounds that include fatty acids (e.g., isovaleric acid), sulfur containing compounds (e.g., mercaptans and sulfides), ammonia, amines (e.g., triethylamine), ketones (e.g., 4-heptanone), alcohols, and aldehydes (decanal) which contribute to the unpleasant odors which can be released from these products during wear or upon disposal. The compounds may be present in the bodily fluids or may develop over time by chemical reaction and/or fluid degradation mechanisms once the fluid has been absorbed into the absorbent article. In addition, once the bodily fluids have been absorbed into the absorbent article, they usually come in contact with microorganisms and/or enzymes that can also generate malodorous by-products as a result of degradation mechanisms such as putrefactive degradation, acid degradation, protein degradation, fat degradation, and the like. These odors can lead to unpleasant experiences for the wearer of the absorbent article and caregiver alike and can make the discreet use and/or disposal of the absorbent articles difficult.
Various odor control materials, agents, techniques, and systems have been disclosed in the art to combat some of the unpleasant odors referred to above, including masking (i.e., covering the odor with a perfume), absorbing the odor already present in the bodily fluids and those generated after degradation, or preventing the formation of the odor. Most of the focus in the prior art is on odor adsorption technology. Examples of these types of compounds include activated carbons, clays, zeolites, silicates, absorbing gelling materials, starches, cyclodextrin, ion exchange resins, and various mixtures thereof (see, for example, EP-A-348 978, EP-A-510 619, WO 91/12029, WO 91/11977, WO 89/02698, and/or WO 91/12030). Odor control systems of the prior art are one-dimensional. For instance, mechanisms where the malodorous compounds and their precursors are physically adsorbed by odor control agents, and thereby hindered from exiting the articles, are not completely effective as the formation of the odor itself is not prevented, and thus odor detection is not completely avoided. Additionally, fragrances are typically used within absorbent articles to enhance the user experience with the product (e.g., fresh-scent bursts). These fragrances are often added at low levels and provide only a marginal odor control benefit over the entire use cycle of the product. Further, adsorbent technologies (e.g., activated carbon) are often not compatible with fragrances because they can be adsorbed and removed from the absorbent article by the adsorbent technologies of the prior art. Thus, although prior art odor control materials provide some control of odors associated with bodily fluids, there still exists a need to provide multidimensional and compatible odor control agents and systems.
It is an object of the present invention to provide effective odor control over a wider range of malodorous compounds and to provide that odor control benefit in instances when fragrance may be present in the absorbent article. Additionally, it is an object of the present invention to provide disposable absorbent articles which provide multiple mechanisms for combating odor, including, but not limited to, reacting with the odor causing molecules and preventing the formation of malodors.
It has been found that the objects of the present inventions are accomplished by using a bleach activator system. An embodiment of a bleach activator system of the present invention is a combination of sodium percarbonate and sodium nonanoyloxybenzenesulfonate (NOBS), which is capable of generating a peroxyacid in-situ within a disposable absorbent article to control malodor.
The laundry industry developed a class of materials known as “bleach activators”. Bleach activators, typically perhydrolyzable acyl compounds having a leaving group such as oxybenzenesulfonate (OBS), react with the active oxygen group, typically hydrogen peroxide or its anion, to form a more effective peroxyacid oxidant. In the laundry context, it is the peroxyacid compound which then oxidizes the stained or soiled substrate. While hydrogen peroxide at modest concentrations can bleach effectively at temperatures of about 60° C. and above, use of bleach activators enables effective bleaching at significantly lower temperatures. Numerous substances have been disclosed in the art as effective bleach activators. One widely-used bleach activator is tetraacetyl ethylene diamine (TAED). Another type of activator, such as nonanoyloxybenzenesulfonate (NOBS) and other activators which generally comprise long chain alkyl moieties, yields a peracid that is hydrophobic in nature and provides excellent performance on dingy stains
Surprisingly, bleach activator systems that generate in-situ peroxyacids can be used in absorbent articles for significantly decreasing bodily odor. These results are evident when absorbent articles comprising a bleach activator system of the present system are compared to the same absorbent article not having the bleach activator system. While not wishing to be bound to theory, it is speculated that the peroxyacids formed in-situ according to the present invention have a dual odor control mechanism: first, they prevent the generation of odor in the absorbent article by blocking enzymatic and/or microbial activity; and second, they combat the odors already present in the absorbent article by oxidizing them into non-odiferous molecules.
In contrast to the use of pre-formed peroxyacids of the prior art, bleach activator systems of the present invention generate the reactive odor control agents only when they are most needed in the absorbent article (i.e., at the time of collection of the waste bodily fluid (e.g., urine, menstrual fluid, and runny bowel exudates)). This is advantageous with reactive materials such as peroxyacids because it lessens the possibility that the material will prematurely react with other materials found in the absorbent article prior to use and it increases the likelihood that the reactive odor control agents are available when needed (e.g., post urine insult). In this way, bleach activator systems of the present invention comprise precursor peroxyacids that are activatable.
Additionally, in-situ generation of peroxyacids via bleach activator systems described herein offers the distinct advantage that they can be used in the presence of a wide variety of fragrance materials. Because formation of the peroxyacid is generated by the bleach activator system upon contact with aqueous media, significant reductions in the concentration of the perfume raw materials prior to insult (due to incompatibility with the peroxyacid or adsorption on the surface of the odor control media) is avoided and enables the fragrance to enhance the overall product experience, especially upon initial opening of the product packaging.
An additional advantage of the in-situ generated peroxyacids of the present invention is that the generation of malodorous smelling by-products like chlorine derivatives and ammonium derivatives is avoided when they come into contact with bodily fluids. In contrast to the in-situ generated peroxyacids of the present invention, oxidants like persulphate, periodate, percarbonate, and/or perborate oxidize the chlorides usually present in bodily fluids into chlorine derivatives that are not acceptable to the consumer from an odor point of view. Also in contrast to the in-situ generated peroxyacids of the present invention, oxidants like urea peroxides, calcium peroxides, strontium peroxides and/or barium peroxides (i.e., compounds having an alkaline pH) promote the formation of malodorous ammonia derivatives (i.e., one of the by-products of proteins degradation occurring in the bodily fluids when they come into contact with it).